Heat shrinking polyester film roll

ABSTRACT

A built-in antenna having: a support body that has a top surface shape having a flat plane that has three neighboring sides with two corners defined therebetween and inclined planes that extend downward from the respective three sides and has other planes between the inclined planes; and a metal conductor that is mounted on the support body, the metal conductor having a shape corresponding to the top surface shape of the support body, the shape being formed by bending a metal plate. The metal conductor has a first slit located corresponding to a middle side of the three sides and a second slit located extending downward from one of the two corners, the second slit being communicated with the first slit and having an opened end.

The present application is based on Japanese patent application No.2002-178376, the entire contents of which are incorporated herein byreference.

TECHNICAL FIELD

This invention relates to an antenna incorporated in device (hereinreferred to as built-in antenna) and a mobile terminal incorporating thesame, and more particularly to a built-in antenna that a metal conductorwith a polyhedral shape formed by bending is tightly fitted on a supportbody and a wide-band mobile terminal incorporating the same.

BACKGROUND ART

Conventionally, as an antenna for mobile apparatus in mobilecommunication, an external type antenna such as a rod antenna and ahelical antenna is provided protruding from the housing of a mobileterminal.

However, the protruding antenna has drawbacks that it interferes withhandling and is subjected to breakage. Moreover, it is not desirablefrom the aspect of design. Therefore, built-in antennas are apt tosubstitute for the external type antenna.

FIG. 1 shows the general composition of a mobile terminal (cellularphone) equipped with a built-in antenna. The cellular phone is composedof a printed-circuit board 101, a liquid crystal 102, an RF circuit 104housed in a shield case 103 on the back of the board 101, an antenna 105and a battery 106. These components are compactly housed in a housing107.

As shown in this composition, the antenna 105 is generally incorporatedat the upper portion of housing because its user holds the lower portionof housing 107 in phone call. Thus, the periphery of antenna 105 is keptnot to be shielded with the hand of user and a good line for calling canbe secured. The built-in antenna is able to solve all the drawbacks ofexternal type antenna and to provide a cellular phone with good functionand design.

FIG. 2 shows the general structure of built-in antenna 105. The built-inantenna 105 is composed of an insulative support body 108 withpolyhedral portion formed on the top, and a metal conductor 109 that isformed by pressing and bending a copper plate etc. to have a shape to betightly fitted on the support body 108. These are integrated using anadhesive agent etc. 110 is a slit formed in the metal conductor 109 toadjust the resonance frequency, 111 is a feeder terminal and 112 is aground terminal.

By the way, it is required that the metal conductor 109 has a volume asmuch as possible to secure a wider band characteristic since there is aproblem that built-in antennas have a band characteristic narrower thanexternal type antennas. Therefore, the shape is made to be polyhedralrather than flat plane. Namely, as shown in FIG. 2, the top of supportbody 108 is composed of a flat plane 113 and inclined planes 114, 115extending downward from the flat plane 113, and the metal conductor 109is formed into a shape to be fitted thereto by bending. The metalconductor 109 thus formed has a volume greater than that of flat platetype, and the band characteristic thereof is enlarged by that much.

FIG. 3 shows a built-in antenna that is suggested to have a furtherenlarged band characteristic.

The built-in antenna in FIG. 3 is composed such that the support body108 and metal conductor 109 shown in FIG. 2 are extended as shown bydouble-dashed chain lines in FIG. 3. Surfaces (116) to (118) are addedboth to the support body 108 and metal conductor 109 and, therefore, thevolume of metal conductor 109 is further increased to further enlargethe band characteristic. The feeder terminal 111 and ground terminal 112are, of course, provided on the surface (117).

The polyhedral shape thus formed is desirable not only for enhancementin antenna property but also for housing easily the antenna in the upperportion of housing 107 that is formed, as shown in FIG. 1, tapered tomeet the demand of design. Thus, the built-in antenna thus composedoffers a good utility to various mobile terminals such as a cellularphone.

However, in the built-in antenna shown in FIG. 3, it is difficult toform the four surfaces (117), (118), 119 and 120 of metal conductor 109by bending without having any strain at, e.g., the corner A of flatplane 113. Therefore, when the metal conductor 109 is mounted on thesupport body 108, excessive part of copper plate to be generated bybending may form uneven region at particularly bended portions among thesurfaces (117), (118), 119 and 120. Such an uneven region may be alsoformed at the opposite corner B.

As a result, there may occur a deviation in band characteristic betweendevices due to the uneven region formed in the vicinity of the bendedportions of metal conductor 109. Further, when mounting the metalconductor 109 on the support body 108, there may occur a gap in thevicinity of bended portions. Therefore, the metal conductor 109 may benot stably held by the support body and, therefore, the bandcharacteristic may be affected adversely.

DISCLOSURE OF INVENTION

It is an object of the invention to provide a built-in antenna withstable band characteristic as well as wide band characteristic and awide band characteristic mobile terminal equipped with the built-inantenna.

According to first aspect of the invention, a built-in antenna,comprises:

a support body that has a top surface shape composed of a flat planethat has three neighboring sides with two corners defined therebetweenand inclined planes that extend downward from the respective three sidesand include other planes between the inclined planes; and

a metal conductor that is mounted on the support body, the metalconductor having a shape corresponding to the top surface shape of thesupport body, the shape being formed by bending a metal plate;

wherein the metal conductor includes a first slit located correspondingto a middle side of the three sides and a second slit located extendingdownward from one of the two corners, the second slit being communicatedwith the first slit and having an opened end.

According to second aspect of the invention, a mobile terminal,comprises:

an antenna that is housed in the mobile terminal and is composed of asupport body and a metal conductor with a predetermined shape to bemounted on the support body;

wherein the antenna is composed of the support body that has a topsurface shape composed of a flat plane that has three neighboring sideswith two corners defined therebetween and inclined planes that extenddownward from the respective three sides and include other planesbetween the inclined planes, and the metal conductor that is mounted onthe support body, the metal conductor having a shape corresponding tothe top surface shape of the support body, the shape being formed bybending a metal plate, and the metal conductor includes a first slitlocated corresponding to a middle side of the three sides and a secondslit located extending downward from one of the two corners, the secondslit being communicated with the first slit and having an opened end.

According to third aspect of the invention, a built-in antenna,comprises:

a support body that has a top surface shape composed of a polygonal flatplane, three first inclined planes that extend inclining downward fromthree neighboring sides of sides to define the flat plane, and at leasttwo second inclined planes to connect between each pair of the threefirst inclined planes; and

a metal conductor that is mounted on the support body, the metalconductor having a shape corresponding to the top surface shape of thesupport body, the shape being formed by bending a metal plate;

wherein the metal conductor includes a slit that is formed by cutting soas to expose the periphery of a corner surrounded by the flat plane,neighboring two of the first inclined planes and the second inclinedplane to connect between the neighboring two of the first inclinedplanes.

In the built-in antenna described above, it is preferred that the topsurface of support body and the metal conductor have a compositiondescribed below.

Namely, it is preferred that the top surface of the support body and themetal conductor include the flat plane of rectangular form, firstinclined planes extending downward from the respective three sides andtwo second inclined planes located at the respective two corners, thesecond inclined planes connecting between the first inclined planes,such that the top surface of the support body and the metal conductorare shaped to be fitted to each other; and the metal conductor has thesecond slit between one end of the first inclined plane extendingdownward from the middle side of the three sides and one of the secondinclined planes. This is an optimum composition when the antenna shownin FIG. 3 is composed applying the invention.

Also, it is preferred that the first and second slits are shaped bypressing such that they have a width that gradually increases from abase portion of the first slit to the opened end of the second slit. Bythus pressing, the width of slit can be kept constant that is likely tonarrow in the direction of the opened end in the process of bending.

The metal plate to compose the metal conductor may be a copper plate orphosphor bronze plate. The material of support body may be variousplastics such as ABS resin and carbonate resin.

BRIEF DESCRIPTION OF DRAWINGS

The preferred embodiments according to the invention will be explainedbelow referring to the attached drawings, wherein:

FIGS. 1(a) to (c) are front, side and back views showing a cellularphone equipped with the conventional built-in antenna;

FIG. 2 shows the conventional built-in antenna;

FIG. 3 shows the suggested built-in antenna with further enlarged bandcharacteristic;

FIG. 4 shows a built-in antenna in a preferred embodiment according tothe invention;

FIG. 5 shows a method of making the built-in antenna shown in FIG. 4;and

FIG.6 shows a modification of the method shown in FIG. 5.

BEST MODE FOR CARRYING OUT THE INVENTION

The preferred embodiments of the invention are explained below withreference to the attached drawings.

In FIG. 4, 1 indicates a support body, and the upper part of supportbody 1 is composed of a rectangular flat plane 2, first inclined planes3 a, 3 b and 3 c that are formed inclining downward from three sides a,b and c of four sides defining the flat plane 2 while having twoneighboring corners C, D therebetween, and second inclined planes 4, 5which respectively connect between the first inclined planes 3 a, 3 band between the first inclined planes 3 b, 3 c.

6 indicates a metal conductor that is made by pressing and bending acopper plate. The metal conductor 6 has a polyhedral shape to be fittedto the shape of upper portion of support body 1. It is attached on thesupport body 1 to be integrally contacted thereto.

As shown in FIG. 4, the metal conductor 6 is composed of a flat plane 20that is defined on the flat plane 2 of support body 1 while having aslit 12, an inclined plane 21 that is defined by being bent along thefirst inclined plane 3 a of support body 1 while connecting with theflat plane 20, an inclined plane 9 that is defined by being bent alongthe second inclined plane 4 of support body 1 while connecting with theinclined plane 21, an inclined plane 22 that is defined by being bentalong the first inclined plane 3 c of support body 1 while connectingwith the flat plane 20, an inclined plane 10 that is defined by beingbent along the second inclined plane 5 of support body 1 whileconnecting with the inclined plane 22, and an inclined plane 8 that isdefined by being bent along the first inclined plane 3 b of support body1 while connecting with the inclined plane 10. The slit 12 extends onthe first inclined plane 3 c and extends along the side c to the cornerD of support body 1.

The metal conductor 6 is further composed of a first slit 7 that extendsalong the side b defining the flat plane 2 of support body 1 whileexposing the side b, corner D and the periphery thereof, and a secondslit 11 that extends along a ridge line 23 between the first inclinedplane 3 b and the second inclined plane 4 of support body 1 whileexposing the ridge line 23, corner C and the periphery thereof. Thesecond slit 11 is formed such that it connects with the first slit 7 atthe one end and has an opening at the other end.

Meanwhile, the slit 12 is formed to adjust the resonance frequency and,in this embodiment, part thereof is shared with the first and secondslits 7, 11. 13 indicates a feeder terminal formed at the lower end ofthe inclined plane 8 of metal conductor 6 being located on the firstinclined plane 3 b, and 14 indicates a ground terminal.

In the built-in antenna of the embodiment thus composed, the first slit7 and second slit 11 formed in the metal conductor 6 serve to eliminateor absorb excessive part of copper plate to be generated by bending.Therefore, the metal conductor 6 can be tightly fitted to the supportbody 1 without incurring any gap although it has a polyhedral shape.

A mobile terminal incorporating the built-in antenna is, of course,provided with a good wide band characteristic based on the antenna withpolyhedral shape. Furthermore, when the built-in antenna is formed asshown in FIG. 4, the antenna can be easily housed in the tapered topportion of housing 107 as shown in FIG. 1 to give the cellular phone agood design.

Although in this embodiment the first inclined planes 3 a, 3 b and 3 cand the second inclined planes 4, 5 are formed only on one side, thesemaybe added on the opposite side if necessary. Also, the flat plane 2may be formed polygonal other than rectangular and, in that case, thenumber of first and second inclined planes may be changed correspondingto that.

FIG. 5 shows a method of making the built-in antenna shown in FIG. 4.Step 1 shows the composition of copper plate before bending. The copperplate is formed by pressing into such a given shape that has the slit 12including the first slit 7 and second slit 11, the feeder terminal 13and ground terminal 14.

Then, in step 2, the copper plate is bent a predetermined angle at foldlines E, F in the direction of arrows G, H. Further, in step. 3, it isbent a predetermined angle at a fold line I, which runs through thefirst slit 7 while lying perpendicular to the fold lines E, F, in thedirection of an arrow J. Then, in step 4, the terminals 13, 14 are benta predetermined angle at a fold line K in the direction of an arrow L.

In step 5, the metal conductor 6 thus shaped by bending is thenintegrally attached on the support body 1 by using a given means. Thus,as shown by “completed” in FIG. 5 (or as show in FIG. 4), the built-inantenna with the predetermined polyhedral shape can be obtained.

In the process shown in FIG. 5, the copper plate after pressing isformed into the metal conductor 6 only by bending. Therefore, thepolyhedral antenna can be made at an advantageously lowcost. This isbrought by that the first slit 7 and second slit 11 of the metalconductor 6 are formed corresponding to the top shape of support body 1that has the inclined planes 3 a, 4 and 3 b and the inclined planes 3 b,5 and 3 c formed in the periphery of the corners C and D, respectively,of flat plane 2.

FIG.6 shows the modified form of copper plate after pressing availablein the process in FIG. 5. The difference from that in FIG. 5 is that thewidth of first slit 7 and second slit 11 is gradually increased in thedirection of from the base portion of first slit 7 to the opened end ofsecond slit 11.

By thus forming the width of slits 7, 11, the width of slit 7, 11 can bekept constant that is likely to narrow in the direction of the openedend of second slit 11 in the process of bending. Such a pressingtechnique is practical and employed in many cases.

INDUSTRIAL APPLICABILITY

According to the invention, there are provided a built-in antenna withstable band characteristic as well as wide band characteristic and awide band characteristic mobile terminal equipped with the built-inantenna.

1. A built-in antenna, comprising: a support body that has a top surfaceshape composed of a flat plane that has three neighboring sides with twocorners defined therebetween and inclined planes that extend downwardfrom the respective three sides and include other planes between theinclined planes; and a metal conductor that is mounted on the supportbody, the metal conductor having a shape corresponding to the topsurface shape of the support body, the shape being formed by bending ametal plate; wherein the metal conductor includes a first slit locatedcorresponding to a middle side of the three sides and a second slitlocated extending downward from one of the two corners, the second slitbeing communicated with the first slit and having an opened end.
 2. Thebuilt-in antenna according to claim 1, wherein: the top surface of thesupport body and the metal conductor include the flat plane ofrectangular form, first inclined planes extending downward from therespective three sides and two second inclined planes located at therespective two corners, the second inclined planes connecting betweenthe first inclined planes, such that the top surface of the support bodyand the metal conductor are shaped to be fitted to each other; and themetal conductor has the second slit between one end of the firstinclined plane extending downward from the middle side of the threesides and one of the second inclined planes.
 3. The built-in antennaaccording to claim 1, wherein: the metal conductor is formed by bendingthe metal plate being shaped by pressing such that the first and secondslits have a width that gradually increases from one end of the firstslit where the first slit is not connected with the second slit to theopened end of the second slit.
 4. A mobile terminal, comprising: anantenna that is housed in the mobile terminal and is composed of asupport body and a metal conductor with a predetermined shape to bemounted on the support body; wherein the antenna is composed of thesupport body that has a top surface shape composed of a flat plane thathas three neighboring sides with two corners defined therebetween andinclined planes that extend downward from the respective three sides andinclude other planes between the inclined planes, and the metalconductor that is mounted on the support body, the metal conductorhaving a shape corresponding to the top surface shape of the supportbody, the shape being formed by bending a metal plate, and the metalconductor includes a first slit located corresponding to a middle sideof the three sides and a second slit located extending downward from oneof the two corners, the second slit being communicated with the firstslit and having an opened end.
 5. A built-in antenna, comprising: asupport body that has a top surface shape composed of a polygonal flatplane, three first inclined planes that extend inclining downward fromthree neighboring sides of sides to define the flat plane, and at leasttwo second inclined planes to connect between each pair of the threefirst inclined planes; and a metal conductor that is mounted on thesupport body, the metal conductor having a shape corresponding to thetop surface shape of the support body, the shape being formed by bendinga metal plate; wherein the metal conductor includes a slit that isformed by cutting so as to expose the periphery of a corner surroundedby the flat plane, neighboring two of the first inclined planes and thesecond inclined plane to connect between the neighboring two of thefirst inclined planes.